Typical swashplate pumps and motors can include a rotating cylinder containing pistons. An auxiliary cam plate holds the pistons against a stationary swash plate which sits at an angle to the cylinder. In pump mode, the device converts mechanical energy into hydraulic pressure. A pair of port openings is in selective communication with the pistons. The pistons pull in fluid during half a revolution when they are in communication with one of the port openings and push fluid out under pressure during the other half of the revolution when they are in communication with the other of the port openings. The port openings allow the pistons to draw in fluid as they move away from the port plate and discharge it as they move toward the port plate. For a given speed, swashplate pumps can be of fixed displacement, or can be variable by being equipped with a variable angle swashplate to correspondingly vary the pump displacement for that speed. The greater the swashplate angle, the more the pistons reciprocally translate and the more fluid they transfer. In motor mode, the swashplate motor converts hydraulic pressure into mechanical torque and angular displacement of a shaft. The swashplate motor operates in a similar, but reverse, fashion as a swashplate pump.
U.S. Pat. No. 5,052,898 is entitled, “Bent Axis Compressor,” and is directed to a bent-axis compressor in which a plurality of spaced bent-axis double acting reciprocating pistons are operatively joined to two separate rotatable cylinder blocks driven by a power transmission around a stationary bent axis central shaft. The central shaft and the pistons are hollow. A vapor inlet port is located at the center of each piston at the plane joining the two halves of the piston and on the side having an exterior obtuse included angle between the two halves. Valved passageways lead from inside the piston to each head of the respective cylinder and from the cylinder head to the interior of the central shaft for exit therefrom as a compressed vapor.
There is a continued need in the art to provide additional solutions for hydraulic pump/motors. For example, there is a continued need for a relatively simple hydraulic device that can use different types of fluids in addition to hydraulic oil as the working fluid. It can be difficult to operate swashplate pumps/motors using a fluid other than hydraulic oil.
It will be appreciated that this background description has been created by the inventor to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some respects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.